Core body thermometer

ABSTRACT

A core body thermometer includes a substrate, a heat receiving terminal with which heat from a subject is received and which divides the heat into first heat flow and second heat flow and causes the first heat flow and the second heat flow to flow out, a first heat flow measurement system that measures the first heat flow using a first input-side temperature sensor and a first output-side temperature sensor, a second heat flow measurement system that measures the second heat flow using a second input-side temperature sensor and a second output-side temperature sensor, a first thermal resistance body provided between the heat receiving terminal and the first input-side temperature sensor, and a second thermal resistance body provided between the heat receiving terminal and the second input-side temperature sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2015-100039 filed on May 15, 2015 and is a ContinuationApplication of PCT Application No. PCT/JP2016/063553 filed on May 2,2016. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a core body thermometer that measuresthe core body temperature of a subject.

2. Description of the Related Art

Non-heating-type thermometers including two pairs of heat flow detectionstructures are generally known as thermometers that measures the corebody temperatures of subjects (for example, refer to Japanese UnexaminedPatent Application Publication No. 2013-200152). The two pairs of heatflow detection structures are each composed of a certain thermalresistance, a first temperature sensor, and a second temperature sensor.The thermal resistance is sandwiched between the first temperaturesensor and the second temperature sensor. In contrast, heating-typethermometers using heating elements (heaters) are also known asthermometers that measure the core body temperatures of subjects (forexample, refer to Japanese Examined Patent Application Publication No.S56-4848).

The non-heating-type thermometer described in Japanese Unexamined PatentApplication Publication No. 2013-200152 detects the difference betweenthe temperatures detected by the first and second temperature sensorswith the respective high-frequency detection structures to calculate theheat flow from deep portions of a subject, so as to calculate the corebody temperature. However, since the two temperature sensors that are incontact with the body surface of the subject are provided in thisconfiguration, the heat is input into the thermometer at two nodes.Accordingly, the thermal resistance in the subject is varied dependingon the location because the tissue of the subject and the shape of thetissue are varied depending on the location. There is a problem in thatthe variation in the thermal resistance in the subject results inuncertain factors in the measurement of the body temperature to degradethe accuracy in the calculation of the core body temperature.

The heating-type thermometer described in Japanese Examined PatentApplication Publication No. S56-4848 has a configuration in which thefirst and second temperature sensors are arranged so as to sandwich theheat insulating body therebetween and the heating element is arranged onthe second temperature sensor with the heat insulating body sandwichedbetween the heating element and the second temperature sensor. In theheating-type thermometer, the difference in temperature between thefirst temperature sensor and the second temperature sensor is made equalto zero by controlling the heating element so that the temperature ofthe first temperature sensor at the subject side is balanced with thetemperature of the second temperature sensor at the heating element sideto calculate the core body temperature. However, since the heatingelement is provided in this configuration, there is a problem in thatcurrent consumption is increased. In addition, the manufacturing costmay possibly be increased due to a control circuit for the heatingelement.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide core bodythermometers that include no heat source for heat generation and thatestimate the core body temperature by receiving the heat from a subjectat one node.

A preferred embodiment of the present invention includes a core bodythermometer that estimates a core body temperature of a subject based ona first heat flow and a second heat flow flowing from the subject. Thecore body thermometer includes a substrate; a heat receiving terminalwhich is provided on the substrate, with which heat from the subject isreceived, and which divides the heat into the first heat flow and thesecond heat flow and causes the first heat flow and the second heat flowto flow out; a first heat flow measurement system that measures thefirst heat flow using a first input-side temperature sensor located atan upstream side of the first heat flow and a first output-sidetemperature sensor located at a downstream side of the first heat flow;a second heat flow measurement system that measures the second heat flowusing a second input-side temperature sensor located at an upstream sideof the second heat flow and a second output-side temperature sensorlocated at a downstream side of the second heat flow; a first thermalresistance body that is provided between the heat receiving terminal andthe first input-side temperature sensor and that has a predeterminedthermal resistance value; and a second thermal resistance body that isprovided between the heat receiving terminal and the second input-sidetemperature sensor and that has a predetermined thermal resistancevalue.

In a core body thermometer according to a preferred embodiment of thepresent invention, the first thermal resistance body is provided as afirst thermal resistance layer laminated between the heat receivingterminal and the first input-side temperature sensor, and the secondthermal resistance body is provided as a second thermal resistance layerlaminated between the heat receiving terminal and the second input-sidetemperature sensor.

In a core body thermometer according to a preferred embodiment of thepresent invention, the first thermal resistance body is provided as afirst thermal resistance component, and the second thermal resistancebody is provided as a second thermal resistance component.

A core body thermometer according to a preferred embodiment of thepresent invention includes one pair of thermal conductive plates thatsandwich the substrate with the heat receiving terminal and multiplevias that pass through the substrate and that connect the heat receivingterminal to the one pair of thermal conductive plates. The first thermalresistance body is provided between one of the thermal conductive platesand the first input-side temperature sensor, and the second thermalresistance body is provided between the other of the thermal conductiveplates and the second input-side temperature sensor.

A core body thermometer according to a preferred embodiment of thepresent invention estimates a core body temperature of a subject basedon first heat flow and second heat flow flowing from the subject. Thecore body thermometer includes a substrate having a predeterminedthermal resistance value; a heat receiving terminal that is provided onone surface of the substrate and that divides heat received from thesubstrate into the first heat flow and the second heat flow and causesthe first heat flow and the second heat flow to flow out; a first heatflow measurement system that is provided on the other surface of thesubstrate and that measures the first heat flow using a first input-sidetemperature sensor located at an upstream side of the first heat flowand a first output-side temperature sensor located at a downstream sideof the first heat flow; and a second heat flow measurement system thatis provided on the other surface of the substrate and that measures thesecond heat flow using a second input-side temperature sensor located atan upstream side of the second heat flow and a second output-sidetemperature sensor located at a downstream side of the second heat flow.

A core body thermometer according to a preferred embodiment of thepresent invention includes a first input-side heat insulating bodyprovided between the first input-side temperature sensor and the firstoutput-side temperature sensor so as to cover the first input-sidetemperature sensor and a second input-side heat insulating body placedbetween the second input-side temperature sensor and the secondoutput-side temperature sensor so as to cover the second input-sidetemperature sensor.

A core body thermometer according to a preferred embodiment of thepresent invention further includes a first output-side heat insulatingbody that covers the first output-side temperature sensor and/or asecond output-side heat insulating body that covers the secondoutput-side temperature sensor.

A core body thermometer according to a preferred embodiment of thepresent invention further includes a charging circuit that charges thecore body thermometer with electric power that is externally supplied ina wireless manner and a transmission circuit that externally transmitsthe core body temperature of the subject, which is estimated with thefirst heat flow measurement system and the second heat flow measurementsystem.

According to a preferred embodiment of the present invention, aconfiguration is provided in which the heat of the subject, input intothe core body thermometer with the heat receiving terminal, is dividedinto the first heat flow and the second heat flow and the core bodytemperature of the subject is estimated based on the first heat flow andthe second heat flow. Since the heat from the subject is input into thecore body thermometer at one node, that is, the single heat receivingterminal, one heat flow occurs from deep portions of the subject to theportion where the heat is input into the core body thermometer. As aresult, even when the thermal resistance in the subject is varied withthe location due to the tissue of the subject and the shape of thetissue, the heat from the subject is capable of being input into thecore body thermometer without being affected by the variation in thethermal resistance in the subject depending on the location.Accordingly, uncertain factors in the measurement of the core bodytemperature are reduced to increase the accuracy in the measurement ofthe core body temperature of the subject.

In addition, according to a preferred embodiment of the presentinvention, the first thermal resistance body is provided between theheat receiving terminal and the first input-side temperature sensor andthe second thermal resistance body is provided between the heatreceiving terminal and the second input-side temperature sensor. Withthis configuration, since the thermal resistance value between the firstheat flow measurement system and the second heat flow measurement systemis high, it is possible to reduce or prevent the heat flow flowing fromthe first heat flow measurement system to the second heat flowmeasurement system (or from the second heat flow measurement system tothe first heat flow measurement system). As a result, the first heatflow measurement system and the second heat flow measurement system arecapable of independently measuring the heat flow input from deepportions of the subject without being affected by the heat flow flowingthrough the other heat flow measurement system. Accordingly, it ispossible to increase the accuracy in the measurement of the core bodytemperature of the subject, compared to a configuration in which thefirst thermal resistance body and the second thermal resistance body areremoved.

Furthermore, according to a preferred embodiment of the presentinvention, a configuration is provided in which the core bodytemperature of the subject is estimated based on the first heat flow andthe second heat flow, which flow from the subject, without using anyheating element. With this configuration, since it is not necessary touse the heat source for heat generation, the power consumption isreduced. In addition, since it is not necessary to use a control circuitfor the heating element, the manufacturing cost of the core bodythermometer is reduced.

According to a preferred embodiment of the present invention, the firstthermal resistance body is laminated between the heat receiving terminaland the first input-side temperature sensor and the second thermalresistance body is laminated between the heat receiving terminal and thesecond input-side temperature sensor. With this configuration, forexample, adjusting the thickness dimensions or the materials of therespective thermal resistance layers enables the thermal resistancevalue between the first heat flow measurement system and the second heatflow measurement system to be easily increased. As a result, it ispossible to reduce or prevent the heat flow flowing between the firstheat flow measurement system and the second heat flow measurement systemto increase the accuracy in the measurement of the core body temperatureof the subject.

According to a preferred embodiment of the present invention, the firstand second thermal resistance bodies are provided as the first andsecond thermal resistance components. Accordingly, since the profiles ofthe first and second thermal resistance bodies are low, compared to thecore body thermometer in which the first and second thermal resistancebodies are laminated, it is possible to reduce the size of the entirecore body thermometer.

According to a preferred embodiment of the present invention, it ispossible to divide the heat (heat flow) received from the subject intothe first heat flow and the second heat flow with the multiple vias andone pair of thermal conductive plates and to supply the first heat flowand the second heat flow to the first heat flow measurement system andthe second heat flow measurement system, respectively. In addition,since the thermal resistance values of the first thermal resistance bodyand the second thermal resistance body are difficult to vary (are lessaffected), for example, if the substrate is deformed (for example,folded), it is possible to reliably and accurately measure the core bodytemperature even if the substrate is deformed.

According to a preferred embodiment of the present invention, thesubstrate has the predetermined thermal resistance value and thesubstrate is capable of being used as the first thermal resistance bodyand the second thermal resistance body described above. In other words,the substrate also has the functions of the first thermal resistancebody and the second thermal resistance body. Accordingly, it is possibleto further simplify the structure of the core body thermometer in orderto reduce the size and weight (make the profile low) and to reduce thecost.

According to a preferred embodiment of the present invention, it ispossible to prevent the influence of the air flow to the firstinput-side temperature sensor and the second input-side temperaturesensor and to make the first input-side temperature sensor and thesecond input-side temperature sensor less affected by the fluctuation ofthe outside air temperature. Accordingly, it is possible to reduce orprevent noise in the outputs from the first input-side temperaturesensor and the second input-side temperature sensor.

According to a preferred embodiment of the present invention, it ispossible to prevent the influence of the air flow to the firstoutput-side temperature sensor and the second output-side temperaturesensor and to make the first output-side temperature sensor and thesecond output-side temperature sensor less affected by the fluctuationof the outside air temperature. Accordingly, it is possible to reduce orprevent noise in the outputs from the first output-side temperaturesensor and the second output-side temperature sensor.

According to a preferred embodiment of the present invention, the corebody thermometer has a configuration in which the core body thermometeris capable of being externally charged in a wireless manner and the corebody temperature of the subject is capable of being externallytransmitted. Accordingly, since the core body thermometer is capable ofbeing used with no cable and the wiring is not used in the measurementof the core body temperature, it is possible to improvenon-invasiveness.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating the configuration of acore body thermometer according to a first preferred embodiment of thepresent invention.

FIG. 2 is a block diagram illustrating the internal configuration of thecore body thermometer according to the first preferred embodiment of thepresent invention.

FIG. 3 is an equivalent circuit diagram illustrating heat flow in thecore body thermometer according to the first preferred embodiment of thepresent invention.

FIG. 4 is a cross-sectional view illustrating the configuration of acore body thermometer according to a second preferred embodiment of thepresent invention.

FIG. 5 is a cross-sectional view illustrating the configuration of acore body thermometer according to a third preferred embodiment of thepresent invention.

FIG. 6 is a block diagram illustrating the internal configuration of thecore body thermometer according to the third preferred embodiment of thepresent invention.

FIG. 7 is a perspective view illustrating a process of providing heatinsulating bodies on a substrate of the core body thermometer accordingto the third preferred embodiment of the present invention.

FIG. 8 is a perspective view illustrating a process of providing theheat insulating bodies on the respective output-side temperaturesensors, following the process in FIG. 7.

FIG. 9 is a cross-sectional view illustrating the configuration of acore body thermometer according to a fourth preferred embodiment of thepresent invention.

FIG. 10 is a cross-sectional view illustrating the configuration of acore body thermometer according to a fifth preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Core body thermometers according to preferred embodiments of the presentinvention will be described in detail with reference to the drawings.

FIG. 1 to FIG. 3 illustrate a first preferred embodiment of the presentinvention. A core body thermometer 1 includes a substrate 2 heatreceiving terminal 3, a first heat flow measurement system 5, a secondheat flow measurement system 11, a first thermal resistance body 10, anda second thermal resistance body 16. The core body thermometer 1estimates a core body temperature Tcore of a subject O based on firstheat flow Ipa and second heat flow Ipb flowing from the subject O.

The substrate 2 preferably has a flat plate shape and is made of aninsulating material, such as polyimide, which has a thermal conductivitylower than that of the subject O. The substrate 2 may be, for example, adeformable flexible substrate or an undeformable printed circuit board.The rear surface (bottom surface) of the substrate 2 is an opposingsurface opposed to the subject O. Accordingly, the heat receivingterminal 3 described below is provided on the rear surface of thesubstrate 2. The front surface (upper surface) of the substrate 2 is amounting surface on which thermal conductive plates 4A and 4B, atemperature measurement circuit 18, an arithmetic processing circuit 20,a battery 21, a memory 22, and other components, which are describedbelow, are mounted.

Vias 2A and 2B passing through the substrate 2 in the thicknessdirection are provided in the substrate 2. The vias 2A and 2B preferablyare formed by forming through holes passing through the substrate 2using laser beam machining or other suitable methods and, for example,plating the through holes with metal conductor. The vias 2A and 2B havethermal conductivity. The heat receiving terminal 3 is connected to thethermal conductive plate 4A through the via 2A and is connected to thethermal conductive plate 4B through the via 2B. A case is exemplified inFIG. 1 in which one via 2A and one via 2B are provided in the substrate2. However, a case in which one via 2A and one via 2B are provided isnot necessarily provided, and multiple vias 2A and multiple vias 2B maybe provided in consideration of the thermal conductivity between theheat receiving terminal 3 and the thermal conductive plates 4A and 4B.

The heat receiving terminal 3 is positioned on the lower surface of thesubstrate 2. The heat receiving terminal 3 preferably has a flat plateshape or a film shape and is made of a material having a thermalconductivity higher than that of the subject O, for example, a metallicmaterial, such as aluminum. The heat receiving terminal 3 is in contactwith the body surface of the subject O and heat from the subject O isinput into the core body thermometer 1 with the heat receiving terminal3. The heat receiving terminal 3 divides the heat from the subject Ointo the first heat flow Ipa and the second heat flow Ipb and causes thefirst heat flow Ipa and the second heat flow Ipb to flow into the vias2A and 2B.

The thermal conductive plate 4A is positioned on the lower surface ofthe first thermal resistance body 10 and is provided on the frontsurface of the substrate 2. The thermal conductive plate 4B ispositioned on the lower surface of the second thermal resistance body 16and is provided on the front surface of the substrate 2. These thermalconductive plates 4A and 4B each preferably have a flat plate shape or afilm shape and are made of a material, such as aluminum, for example,having a high thermal conductivity, similar to the heat receivingterminal 3. The thermal conductive plate 4A is connected to the via 2Aand the thermal conductive plate 4B is connected to the via 2B. Thethermal conductive plate 4A conducts the heat of the subject O, which isinput into the core body thermometer 1 through the heat receivingterminal 3, to the first heat flow measurement system 5 as the firstheat flow Ipa. The thermal conductive plate 4B conducts the heat of thesubject O, which is input into the core body thermometer 1 through theheat receiving terminal 3, to the second heat flow measurement system 11as the second heat flow Ipb.

The first heat flow measurement system 5 is positioned on the uppersurface side of the thermal conductive plate 4A. The first heat flowmeasurement system 5 includes a first input-side temperature sensor 6, afirst input-side heat insulating body 7, a first output-side temperaturesensor 8, and a first output-side heat insulating body 9. In the firstheat flow measurement system 5, the first input-side temperature sensor6 and the first output-side temperature sensor 8 are located atdifferent positions on a path along which the first heat flow Ipa flows.With the above configuration, the first heat flow measurement system 5measures the first heat flow Ipa flowing from the thermal conductiveplate 4A to the upper side of the first heat flow measurement system 5based on temperatures T1 and T2 measured by the first input-sidetemperature sensor 6 and the first output-side temperature sensor 8,respectively.

The first input-side temperature sensor 6 is positioned above thethermal conductive plate 4A (i.e., immediately above the thermalconductive plate 4A) in the thickness direction of the substrate 2 andis provided on the first thermal resistance body 10. In other words, thefirst input-side temperature sensor 6 is located at the upstream side ofthe first heat flow Ipa. The first input-side temperature sensor 6 ispreferably, for example, a thermistor, and measures the temperature T1at the upstream side of the first heat flow Ipa.

The first input-side heat insulating body 7 is positioned on the firstthermal resistance body 10 to cover the first input-side temperaturesensor 6. The first input-side heat insulating body 7 preferably has asheet shape and is made of a material, such as urethane, for example,having a low thermal conductivity. The first input-side temperaturesensor 6 is sandwiched between the first input-side heat insulating body7 and the first thermal resistance body 10. Accordingly, the firstinput-side temperature sensor 6 is blocked from the outside air with thefirst input-side heat insulating body 7 and the first thermal resistancebody 10.

The first input-side heat insulating body 7 is sandwiched between thefirst input-side temperature sensor 6 and the first output-sidetemperature sensor 8. The first input-side heat insulating body 7 has apredetermined thickness dimension. Accordingly, the first input-sideheat insulating body 7 has a predetermined thermal resistance value R1between the first input-side temperature sensor 6 and the firstoutput-side temperature sensor 8 depending on the thickness dimension.

The first output-side temperature sensor 8 is positioned above thethermal conductive plate 4A (i.e., immediately above the thermalconductive plate 4A) in the thickness direction of the substrate 2 andis provided on the first input-side heat insulating body 7. In otherwords, the first output-side temperature sensor 8 is located at thedownstream side of the first heat flow Ipa. The first output-sidetemperature sensor 8 is preferably, for example, a thermistor, andmeasures the temperature T2 at the downstream side of the first heatflow Ipa.

The first output-side heat insulating body 9 is positioned on the firstinput-side heat insulating body 7 to cover the first output-sidetemperature sensor 8. The first output-side heat insulating body 9preferably has a sheet shape and is made of a material, such asurethane, for example, having a low thermal conductivity. The firstoutput-side temperature sensor 8 is sandwiched between the firstoutput-side heat insulating body 9 and the first input-side heatinsulating body 7. Accordingly, the first output-side temperature sensor8 is blocked from the outside air with the first output-side heatinsulating body 9 and the first input-side heat insulating body 7. Inthis case, in order to reduce or prevent the influence of thermalcontact resistance, for example, the first output-side heat insulatingbody 9 and the first input-side heat insulating body 7 preferably havethe same or substantially the same thermal conductivity. Accordingly,the first output-side heat insulating body 9 is preferably made of thesame material as that of the first input-side heat insulating body 7.The first output-side heat insulating body 9 is sandwiched between thefirst output-side temperature sensor 8 and the outside air. The firstoutput-side heat insulating body 9 has a predetermined thicknessdimension. Accordingly, the first output-side heat insulating body 9 hasa predetermined thermal resistance value R2 between the firstoutput-side temperature sensor 8 and the outside air depending on thethickness dimension.

The first thermal resistance body 10 is a first thermal resistance layerlaminated between the heat receiving terminal 3 and the first input-sidetemperature sensor 6. Specifically, the first thermal resistance body 10is provided between the substrate 2 and the first input-side heatinsulating body 7 and is located between the thermal conductive plate4A, which is connected to the heat receiving terminal 3 with the thermalconductivity, and the first input-side temperature sensor 6. The firstthermal resistance body 10 preferably has a sheet shape and is made of amaterial, such as urethane, for example, having a low thermalconductivity. The first thermal resistance body 10 is provided on theupper surface side of the substrate 2 so as to cover the thermalconductive plate 4A.

The first thermal resistance body 10 is sandwiched between the thermalconductive plate 4A and the first input-side temperature sensor 6. Thefirst thermal resistance body 10 has a predetermined thicknessdimension. Accordingly, the first thermal resistance body 10 has apredetermined thermal resistance value Ra between the thermal conductiveplate 4A and the first input-side temperature sensor 6 depending on thethickness dimension.

The thermal resistance value Ra of the first thermal resistance body 10is set in consideration of thermal isolation between the first heat flowmeasurement system 5 and the second heat flow measurement system 11.Accordingly, the first thermal resistance body 10 prevents the heat flowfrom flowing between the first heat flow measurement system 5 and thesecond heat flow measurement system 11 with the second thermalresistance body 16. In this case, in order to reduce or prevent theinfluence of the thermal contact resistance, for example, the firstthermal resistance body 10 and the first input-side heat insulating bodypreferably have the same or substantially the same thermal conductivity.Accordingly, the first thermal resistance body 10 is preferably made ofthe same material as those of the first input-side heat insulating body7 and the first output-side heat insulating body 9.

The second heat flow measurement system 11 is positioned on the uppersurface side of the thermal conductive plate 4B. The second heat flowmeasurement system 11 includes a second input-side temperature sensor12, a second input-side heat insulating body 13, a second output-sidetemperature sensor 14, and a second output-side heat insulating body 15.In the second heat flow measurement system 11, the second input-sidetemperature sensor 12, and the second output-side temperature sensor 14are located at different positions along a path on which the second heatflow Ipb flows. With the above configuration, the second heat flowmeasurement system 11 measures the second heat flow Ipb flowing from thethermal conductive plate 4B to the upper side of the second heat flowmeasurement system 11 based on temperatures T3 and T4 measured by thesecond input-side temperature sensor 12 and the second output-sidetemperature sensor 14, respectively.

The second input-side temperature sensor 12 is positioned above thethermal conductive plate 4B (i.e., immediately above the thermalconductive plate 4B) in the thickness direction of the substrate 2 andis provided on the second thermal resistance body 16. In other words,the second input-side temperature sensor 12 is located at the upstreamside of the second heat flow Ipb. The second input-side temperaturesensor 12 is preferably, for example, a thermistor, and measures thetemperature T3 at the upstream side of the second heat flow Ipb.

The second input-side heat insulating body 13 is positioned on thesecond thermal resistance body 16 to cover the second input-sidetemperature sensor 12. The second input-side heat insulating body 13preferably has a sheet shape and is made of a material, such asurethane, for example, having a low thermal conductivity. The secondinput-side temperature sensor 12 is sandwiched between the secondinput-side heat insulating body 13 and the second thermal resistancebody 16. Accordingly, the second input-side temperature sensor 12 isblocked from the outside air with the second input-side heat insulatingbody 13 and the second thermal resistance body 16.

The second input-side heat insulating body 13 is sandwiched between thesecond input-side temperature sensor 12 and the second output-sidetemperature sensor 14. The second input-side heat insulating body 13 hasa predetermined thickness dimension. Accordingly, the second input-sideheat insulating body 13 has a predetermined thermal resistance value R3between the second input-side temperature sensor 12 and the secondoutput-side temperature sensor 14 depending on the thickness dimension.

The second output-side temperature sensor 14 is positioned above thethermal conductive plate 4B (i.e., immediately above the thermalconductive plate 4B) in the thickness direction of the substrate 2 andis provided on the second input-side heat insulating body 13. In otherwords, the second output-side temperature sensor 14 is located at thedownstream side of the second heat flow Ipb. The second output-sidetemperature sensor 14 is preferably, for example, a thermistor, andmeasures the temperature T4 at the downstream side of the second heatflow Ipb.

The second output-side heat insulating body 15 is positioned on thesecond input-side heat insulating body 13 to cover the secondoutput-side temperature sensor 14. The second output-side heatinsulating body 15 preferably has a sheet shape and is made of amaterial, such as urethane, for example, having a low thermalconductivity. The second output-side temperature sensor 14 is sandwichedbetween the second output-side heat insulating body 15 and the secondinput-side heat insulating body 13. Accordingly, the second output-sidetemperature sensor 14 is blocked from the outside air with the secondoutput-side heat insulating body 15 and the second input-side heatinsulating body 13.

The second output-side heat insulating body 15 is sandwiched between thesecond output-side temperature sensor 14 and the outside air. The secondoutput-side heat insulating body has a predetermined thicknessdimension. Accordingly, the second output-side heat insulating body 15has a predetermined thermal resistance value R4 between the secondoutput-side temperature sensor 14 and the outside air depending on thethickness dimension.

In this case, the second output-side heat insulating body 15 preferablyhas a thickness dimension greater than that of the first output-sideheat insulating body 9 in order to differentiate the heat flow value ofthe first heat flow Ipa from the heat flow value of the second heat flowIpb. Accordingly, the thermal resistance value R4 of the secondoutput-side heat insulating body 15 is higher than the thermalresistance value R2 of the first output-side heat insulating body 9. Inorder to reduce or prevent the influence of the thermal contactresistance, for example, the second output-side heat insulating body 15and the second input-side heat insulating body 13 preferably have thesame or substantially the same thermal conductivity. Accordingly, thesecond output-side heat insulating body 15 is preferably made of thesame material as that of the second input-side heat insulating body 13.

The second thermal resistance body 16 is a second thermal resistancelayer laminated between the heat receiving terminal 3 and the secondinput-side temperature sensor 12. Specifically, the second thermalresistance body 16 is provided between the substrate 2 and the secondinput-side heat insulating body 13 and is located between the thermalconductive plate 4B, which is connected to the heat receiving terminal 3with the thermal conductivity, and the second input-side temperaturesensor 12. The second thermal resistance body 16 preferably has a sheetshape and is made of a material, such as urethane, for example, having alow thermal conductivity. The second thermal resistance body 16 isprovided on the upper side of the substrate 2 so as to cover the thermalconductive plate 4B.

The second thermal resistance body 16 is sandwiched between the thermalconductive plate 4B and the second input-side temperature sensor 12. Thesecond thermal resistance body 16 has a predetermined thicknessdimension. Accordingly, the second thermal resistance body 16 has apredetermined thermal resistance value Rb between the thermal conductiveplate 4B and the second input-side temperature sensor 12 depending onthe thickness dimension.

The thermal resistance value Rb of the second thermal resistance body 16is set in consideration of the thermal isolation between the first heatflow measurement system 5 and the second heat flow measurement system11. Accordingly, the second thermal resistance body 16 prevents the heatflow from flowing between the first heat flow measurement system 5 andthe second heat flow measurement system 11 with the first thermalresistance body 10. In this case, in order to reduce or prevent theinfluence of the thermal contact resistance, for example, the secondthermal resistance body 16 and the second input-side heat insulatingbody 13 preferably have the same or substantially the same thermalconductivity. Accordingly, the second thermal resistance body 16 ispreferably made of the same material as those of the second input-sideheat insulating body 13 and the second output-side heat insulating body15.

The sum (Ra+Rb) of the thermal resistances of the first thermalresistance body 10 and the second thermal resistance body 16 ispreferably set to a value at which the thermal resistance between thefirst input-side temperature sensor 6 and the second input-sidetemperature sensor 12 is higher than that, for example, in a case inwhich the first input-side temperature sensor 6 and the secondinput-side temperature sensor 12 are directly in contact with the bodysurface of the subject O. As illustrated in FIG. 3, when the firstinput-side temperature sensor 6 and the second input-side temperaturesensor 12 are directly in contact with the body surface of the subjectO, a thermal resistance value Rab between the first input-sidetemperature sensor 6 and the second input-side temperature sensor 12 isdetermined by the distance between the first input-side temperaturesensor 6 and the second input-side temperature sensor 12 and the thermalconductivity near the body surface of the subject O. The sum (Ra+Rb) ofthe thermal resistances of the first thermal resistance body 10 and thesecond thermal resistance body 16 is preferably greater than the thermalresistance value Rab (Rab<Ra+Rb).

The sum (Ra+R1+R2) of the thermal resistances of the first thermalresistance body 10, the first input-side heat insulating body 7, and thefirst output-side heat insulating body 9 is preferably set so as to bedifferent from the sum (Rb+R3+R4) of the thermal resistances of thesecond thermal resistance body 16, the second input-side heat insulatingbody 13, and the second output-side heat insulating body 15. As aresult, the first heat flow Ipa has a value different from that of thesecond heat flow Ipb.

The first heat flow measurement system 5 is spaced away from the secondheat flow measurement system 11. Similarly, the first thermal resistancebody 10 is spaced away from the second thermal resistance body 16.Accordingly, a gap 17 is provided between the first heat flowmeasurement system 5 and the second heat flow measurement system 11. Thegap 17 extends to a portion between the first thermal resistance body 10and the second thermal resistance body 16. The gap 17 defines a heatinsulating portion with which the first heat flow measurement system 5is thermally isolated from the second heat flow measurement system 11and thermally isolates the first thermal resistance body 10 from thesecond thermal resistance body 16.

As illustrated in FIG. 2, the temperature measurement circuit 18 definesa portion of a signal processing circuit that calculates the core bodytemperature Tcore of the subject O based on the temperatures T1 to T4measured by the temperature sensors 6, 8, 12, and 14, respectively. Thetemperature measurement circuit 18 is provided on, for example, thesubstrate 2 and is connected to the respective temperature sensors 6, 8,12, and 14. The temperature measurement circuit 18 is preferably definedby, for example, an amplifier and an analog-to-digital converter, whichare not illustrated. The temperature measurement circuit 18 amplifies ananalog signal supplied from each of the temperature sensors 6, 8, 12,and 14, converts the analog signal into a digital signal, and suppliesthe digital signal to the arithmetic processing circuit 20 describedbelow. In addition to the temperature sensors 6, 8, 12, and 14, atemperature sensor 19 is also connected to the temperature measurementcircuit 18. The temperature sensor 19 measures a temperature other thanthe temperature of the subject O (for example, outside air temperature).

The arithmetic processing circuit 20 defines a portion of the signalprocessing circuit, which calculates the core body temperature Tcore ofthe subject O. The arithmetic processing circuit 20 is preferablydefined by, for example, a micro control unit (MCU) and calculates thecore body temperature Tcore of the subject O based on the temperaturesT1 to T4 of the respective temperature sensors 6, 8, 12, and 14, whichare subjected to the signal processing in the temperature measurementcircuit 18. Power is supplied from the battery 21 to the arithmeticprocessing circuit 20. The arithmetic processing circuit 20 stores thecalculated core body temperature Tcore in the memory 22.

The core body thermometer 1 according to the present preferredembodiment is preferably configured as described above. A method ofcalculating the core body temperature Tcore of the subject O using thecore body thermometer 1 will now be described.

First, when the heat receiving terminal 3 of the core body thermometer 1is in contact with the body surface of the subject O, the equivalentcircuit of the heat flow from deep portions of the subject O to theoutside air is illustrated in FIG. 3. In this case, a thermal resistancevalue Rcore in the subject indicates the thermal resistance value of thesubcutaneous tissue of the subject O.

Then, the arithmetic processing circuit 20 calculates the first andsecond heat flows Ipa and Ipb using the temperatures T1 to T4 measuredby the temperature sensors 6, 8, 12, and 14, respectively. In this case,the first and second heat flows Ipa and Ipb are represented by Formula 1and Formula 2, respectively:

$\begin{matrix}{{Ipa} = {\frac{{T1} - {T2}}{R1} = \frac{{Tcore} - {T1}}{{Rcore} + {Ra}}}} & {{Formula}\mspace{14mu} 1} \\{{Ipb} = {\frac{{T3} - {T4}}{R\; 3} = \frac{{Tcore} - {T\; 3}}{{Rcore} + {Rb}}}} & {{Formula}\mspace{14mu} 2}\end{matrix}$

Since the first and second thermal resistance bodies 10 and 16 have theknown thermal resistance values Ra and Rb, respectively, the core bodytemperature Tcore of the subject O is able to be calculated byeliminating the thermal resistance value Rcore using Formula 1 andFormula 2 as a system of equations.

When the thermal resistance value Ra is equal to the thermal resistancevalue Rb, the core body temperature Tcore is able to be calculated usingFormula 3 resulting from a modification of Formula 1 and Formula 2. Inthis case, a constant K is represented by Formula 4.

$\begin{matrix}{{Tcore} = \frac{{\left( {{T\; 3} - {T\; 4}} \right) \times T1} - {{K\left( {{T1} - {T2}} \right)} \times T3}}{\left( {{T\; 3} - {T\; 4}} \right) - {K\left( {{T\; 1} - {T\; 2}} \right)}}} & {{Formula}\mspace{14mu} 3} \\{K = \frac{R3}{R\; 1}} & {{Formula}\mspace{14mu} 4}\end{matrix}$

As described above, according to the first preferred embodiment, aconfiguration is provided in which the heat of the subject O, input intothe core body thermometer 1 with the heat receiving terminal 3, isdivided into the first heat flow Ipa and the second heat flow Ipb andthe core body temperature Tcore of the subject O is calculated based onthe first heat flow Ipa and the second heat flow Ipb. Since the heatfrom the subject O is input into the core body thermometer 1 at onenode, that is, the single heat receiving terminal 3, one heat flowoccurs from deep portions of the subject O to the heat receivingterminal 3. As a result, even when the thermal resistance in the subjectis varied with the location due to the tissue of the subject and theshape of the tissue, the heat from the subject O is able to be inputinto the core body thermometer 1 without being affected by the variationin the thermal resistance in the subject depending on the location.Accordingly, uncertain factors in the measurement of the core bodytemperature are reduced to increase the accuracy in the measurement ofthe core body temperature Tcore of the subject O.

When the first input-side temperature sensor 6 and the second input-sidetemperature sensor 12 are directly in contact with the body surface ofthe subject O, the thermal resistance value Rab between the firstinput-side temperature sensor 6 and the second input-side temperaturesensor 12 is determined by the thermal conductivity near the bodysurface of the subject O. According to the first preferred embodiment,the first thermal resistance body 10 is provided between the heatreceiving terminal 3 and the first input-side temperature sensor 6 andthe second thermal resistance body 16 is provided between the heatreceiving terminal 3 and the second input-side temperature sensor 12.With this configuration, since the thermal resistance value (Ra+Rb)between the first heat flow measurement system 5 and the second heatflow measurement system 11 is higher than the thermal resistance valueRab caused by the subject O, it is possible to reduce or prevent theheat flow flowing between the first heat flow measurement system 5 andthe second heat flow measurement system 11.

As a result, the first heat flow measurement system 5 and the secondheat flow measurement system 11 are able to independently measure theheat flow input from deep portions of the subject O without beingaffected by the heat flow flowing through the other heat flowmeasurement system. Accordingly, it is possible to increase the accuracyin the measurement of the core body temperature Tcore of the subject O,compared to a configuration in which the first and second thermalresistance bodies 10 and 16 are removed. In addition, since the firstheat flow measurement system 5 is able to be located near the secondheat flow measurement system 11, it is possible to reduce the variationin the thermal resistance in the subject near the heat receivingterminal 3.

In addition, according to the first preferred embodiment, aconfiguration is provided in which the core body temperature Tcore ofthe subject O is calculated based on the first heat flow Ipa and thesecond heat flow Ipb, which flow from the subject O, without using anyheating element. With this configuration, since it is not necessary touse the heat source for heat generation, the power consumption isreduced. In addition, since it is not necessary to use a control circuitfor the heating element, the manufacturing cost of the core bodythermometer 1 is reduced.

Furthermore, according to the first preferred embodiment, the firstthermal resistance body 10 is laminated between the heat receivingterminal 3 and the first input-side temperature sensor 6 and the secondthermal resistance body 16 is laminated between the heat receivingterminal 3 and the second input-side temperature sensor 12. With thisconfiguration, for example, adjusting the thickness dimensions or thematerials of the respective thermal resistance bodies 10 and 16 enablesthe thermal resistance value between the first heat flow measurementsystem 5 and the second heat flow measurement system 11 to be easilyincreased. As a result, it is possible to reduce or prevent the heatflow flowing between the first heat flow measurement system 5 and thesecond heat flow measurement system 11 to improve the thermal isolationbetween the first heat flow measurement system 5 and the second heatflow measurement system 11, so as to increase the accuracy in themeasurement of the core body temperature Tcore of the subject O.

According to the present preferred embodiment, one pair of thermalconductive plates 4A and 4B, which sandwich the substrate 2 with theheat receiving terminal 3, and one pair of vias 2A and 2B, which passthrough the substrate 2 and which connects the heat receiving terminal 3to one pair of thermal conductive plates 4A and 4B, respectively, areprovided. The first thermal resistance body 10 is provided between thethermal conductive plate 4A and the first input-side temperature sensor6 and the second thermal resistance body 16 is provided between thethermal conductive plate 4B and the second input-side temperature sensor12. Accordingly, it is possible to divide the heat (heat flow) receivedfrom the subject into the first heat flow Ipa and the second heat flowIpb with one pair of vias 2A and 2B and one pair of thermal conductiveplates 4A and 4B and to supply the first heat flow Ipa and the secondheat flow Ipb to the first heat flow measurement system 5 and the secondheat flow measurement system 11, respectively. In addition, since thethermal resistance values of the first thermal resistance body 10 andthe second thermal resistance body 16 are difficult to vary (are lessaffected), for example, if the substrate 2 is deformed (for example, isfolded), it is possible to stably measure the core body temperature evenif the substrate 2 is deformed.

According to the present preferred embodiment, the first input-side heatinsulating body 7, which is provided between the first input-sidetemperature sensor 6 and the first output-side temperature sensor 8 soas to cover the first input-side temperature sensor 6, and the secondinput-side heat insulating body 13, which is provided between the secondinput-side temperature sensor 12 and the second output-side temperaturesensor 14 so as to cover the second input-side temperature sensor 12,are provided. Accordingly, it is possible to prevent the influence ofthe air flow to the first input-side temperature sensor 6 and the secondinput-side temperature sensor 12 and to make the first input-sidetemperature sensor 6 and the second input-side temperature sensor 12less affected by the fluctuation of the outside air temperature.Consequently, it is possible to reduce or prevent noise in the outputsfrom the first input-side temperature sensor 6 and the second input-sidetemperature sensor 12.

According to the present preferred embodiment, the first output-sideheat insulating body 9, which covers the first output-side temperaturesensor 8, and the second output-side heat insulating body 15, whichcovers the second output-side temperature sensor 14, are preferablyfurther provided. Accordingly, it is possible to prevent the influenceof the air flow to the first output-side temperature sensor 8 and thesecond output-side temperature sensor 14 and to make the firstoutput-side temperature sensor 8 and the second output-side temperaturesensor 14 less affected by the fluctuation of the outside airtemperature. Consequently, it is possible to reduce or prevent noise inthe outputs from the first output-side temperature sensor 8 and thesecond output-side temperature sensor 14.

A second preferred embodiment of the present invention will now bedescribed with reference to FIG. 4. In the second preferred embodiment,a configuration is provided in which the first and second thermalresistance bodies are provided as first and second thermal resistancecomponents, respectively. The same reference numerals are used in thesecond preferred embodiment to identify the same components in the firstpreferred embodiment. A description of such components is omittedherein.

A core body thermometer 31 according to the second preferred embodimentincludes the substrate 2, the heat receiving terminal 3, the first heatflow measurement system 5, the second heat flow measurement system 11,input-side thermal conductive plates 32A and 32B, output-side thermalconductive plates 33A and 33B, a first thermal resistance body 34, and asecond thermal resistance body 35.

The input-side thermal conductive plate 32A and the output-side thermalconductive plate 33A are positioned on the lower side of the first heatflow measurement system 5 and are provided on the surface of thesubstrate 2 in a state in which the input-side thermal conductive plate32A is separated from the output-side thermal conductive plate 33A. Thethermal conductive plates 32A and 33A each preferably have a flat plateshape or a film shape that are made of a material, such as aluminum, forexample, having a high thermal conductivity, similar to the heatreceiving terminal 3. The input-side thermal conductive plate 32A islocated at a position closer to the gap 17, which is at a centralportion of the substrate 2. The input-side thermal conductive plate 32Ais connected to the via 2A. The first input-side temperature sensor 6 inthe first heat flow measurement system 5 is provided on the output-sidethermal conductive plate 33A. The input-side thermal conductive plate32A is thermally connected to the output-side thermal conductive plate33A with the first thermal resistance body 34. Accordingly, theinput-side thermal conductive plate 32A and the output-side thermalconductive plate 33A conduct the first heat flow Ipa divided by the heatreceiving terminal 3 to the first input-side temperature sensor 6.

The input-side thermal conductive plate 32B and the output-side thermalconductive plate 33B are positioned on the lower side of the second heatflow measurement system 11 and are provided on the surface of thesubstrate 2 in a state in which the input-side thermal conductive plate32B is separated from the output-side thermal conductive plate 33B. Thethermal conductive plates 32B and 33B each preferably have a flat plateshape or a film shape and are made of a material, such as aluminum, forexample, having a high thermal conductivity, similar to the heatreceiving terminal 3. The input-side thermal conductive plate 32B islocated at a position closer to the gap 17, which is at the centralportion of the substrate 2. The input-side thermal conductive plate 32Bis connected to the via 2B. The second input-side temperature sensor 12in the second heat flow measurement system 11 is provided on theoutput-side thermal conductive plate 33B. The input-side thermalconductive plate 32B is thermally connected to the output-side thermalconductive plate 33B with the second thermal resistance body 35.Accordingly, the input-side thermal conductive plate 32B and theoutput-side thermal conductive plate 33B conduct the second heat flowIpb divided by the heat receiving terminal 3 to the second input-sidetemperature sensor 12.

The first thermal resistance body 34 is a first thermal resistancecomponent provided between the heat receiving terminal 3 and the firstinput-side temperature sensor 6. Specifically, the first thermalresistance body 34 is provided between the input-side thermal conductiveplate 32A, which is connected to the heat receiving terminal 3 with thethermal conductivity, and the output-side thermal conductive plate 33A,which is separated and spaced from the input-side thermal conductiveplate 32A. The first thermal resistance body 34 preferably has a chipshape and is made of a material, such as urethane, for example, having alow thermal conductivity and has the predetermined thermal resistancevalue Ra.

The thermal resistance value Ra of the first thermal resistance body 34is set in consideration of the thermal isolation between the first heatflow measurement system 5 and the second heat flow measurement system11. Accordingly, the first thermal resistance body 34 prevents the heatflow from flowing between the first heat flow measurement system 5 andthe second heat flow measurement system 11 with the second thermalresistance body 35. The thermal conductivity of the first thermalresistance body 34 is preferably higher than those of the substrate 2and the first input-side heat insulating body 7. With thisconfiguration, the first heat flow Ipa supplied from the heat receivingterminal 3 to the input-side thermal conductive plate 32A passes throughthe first thermal resistance body 34, rather than the first input-sideheat insulating body 7, and is supplied to the first input-sidetemperature sensor 6 through the output-side thermal conductive plate33A.

The second thermal resistance body 35 is a second thermal resistancecomponent provided between the heat receiving terminal 3 and the secondinput-side temperature sensor 12. Specifically, the second thermalresistance body 35 is provided between the input-side thermal conductiveplate 32B, which is connected to the heat receiving terminal 3 with thethermal conductivity, and the output-side thermal conductive plate 33B,which is separated and spaced from the input-side thermal conductiveplate 32B. The second thermal resistance body 35 preferably has a chipshape and is made of a material, such as urethane, for example, having alow thermal conductivity and has the predetermined thermal resistancevalue Rb.

The thermal resistance value Rb of the second thermal resistance body 35is set in consideration of the thermal isolation between the first heatflow measurement system 5 and the second heat flow measurement system11. Accordingly, the second thermal resistance body 35 prevents the heatflow from flowing between the first heat flow measurement system 5 andthe second heat flow measurement system 11 with the first thermalresistance body 34. The thermal conductivity of the second thermalresistance body 35 is preferably higher than those of the substrate 2and the second input-side heat insulating body 13.

The sum (Ra+Rb) of the thermal resistances of the first thermalresistance body 34 and the second thermal resistance body 35 ispreferably greater than the thermal resistance value Rab between thefirst input-side temperature sensor 6 and the second input-sidetemperature sensor 12 (Rab<Ra+Rb), as in the first preferred embodiment.

The sum (Ra+R1+R2) of the thermal resistances of the first thermalresistance body 34, the first input-side heat insulating body 7, and thefirst output-side heat insulating body 9 is preferably set so as to bedifferent from the sum (Rb+R3+R4) of the thermal resistances of thesecond thermal resistance body 35, the second input-side heat insulatingbody 13, and the second output-side heat insulating body 15. As aresult, the first heat flow Ipa has a value different from that of thesecond heat flow Ipb.

As described above, the same or substantially the same effects andadvantages as those of the first preferred embodiment are achieved inthe second preferred embodiment. According to the core body thermometer31 of the second preferred embodiment, the first and thermal resistancebodies 34 and 35 are provided as the first and second thermal resistancecomponents having chip shapes. Accordingly, since the profiles of thefirst and second thermal resistance bodies 34 and 35 is reduced,compared to the core body thermometer in which the first and secondthermal resistance bodies are laminated, it is possible to reduce thesize of the entire core body thermometer 31.

A third preferred embodiment of the present invention will now bedescribed with reference to FIG. 5 to FIG. 8. A configuration isprovided in the third preferred embodiment in which a core bodythermometer includes a charging circuit that charges the core bodythermometer with electric power that is externally supplied in awireless manner and a transmission circuit that externally transmits themeasured core body temperature. The same reference numerals are used inthe third preferred embodiment to identify the same components in thefirst and second preferred embodiments. A description of such componentsis omitted herein.

A core body thermometer 41 according to the third preferred embodimentincludes a disposable film portion 42 (a disposable portion) and arepeatedly usable main body 52 (a repeatedly usable portion), asillustrated in FIG. 5 and FIG. 6. The film portion 42 includes asubstrate 43, the heat receiving terminal 3, the first heat flowmeasurement system 5, a second heat flow measurement system 46, theinput-side thermal conductive plates 32A and 32B, the output-sidethermal conductive plates 33A and 33B, the first thermal resistance body34, and the second thermal resistance body 35.

The substrate 43 is preferably made of an insulating material, such aspolyimide, for example, which has a thermal conductivity lower than thatof the subject O. In this case, the substrate 43 is preferably made of,for example, a deformable flexible substrate. The substrate 43 includesa heat receiving portion 43A that is in contact with the subject O andreceives heat from the subject O, a first arm portion 43B that extendsfrom the heat receiving portion 43A towards the outside, a second armportion 43C, a connection terminal portion 43D, and an antenna portion43E. The first output-side temperature sensor 8 is provided on the firstarm portion 43B. The second output-side temperature sensor 14 isprovided on the second arm portion 43C. Substrate-side connectionterminals 44A and 44B for electrical connection to the main body 52 areprovided on the connection terminal portion 43D. The substrate-sideconnection terminal 44A is connected to the arithmetic processingcircuit 20 and the substrate-side connection terminal 44B is connectedto a voltage stabilizing circuit 51. A harvesting antenna 50 describedbelow is provided on the antenna portion 43E.

Vias 45A and 45B passing through the substrate 43 in the thicknessdirection are provided in the substrate 43. The heat receiving terminal3 is connected to the input-side thermal conductive plate 32A throughthe via 45A and is connected to the input-side thermal conductive plate32B through the via 45B.

The front surface (upper surface) of the substrate 43 is a mountingsurface on which the input-side thermal conductive plates 32A and 32B,the output-side thermal conductive plates 33A and 33B, the first thermalresistance body 34, the second thermal resistance body 35, thetemperature measurement circuit 18, the arithmetic processing circuit20, a harvesting integrated circuit (IC) 49, the harvesting antenna 50,the voltage stabilizing circuit 51, and other components are mounted, asillustrated in FIG. 5 and FIG. 7.

The second heat flow measurement system 46 is positioned on the upperside of the output-side thermal conductive plate 33B and is provided onthe substrate 43. The second heat flow measurement system 46 includesthe second input-side temperature sensor 12, a second input-side heatinsulating body 47, the second output-side temperature sensor 14, and asecond output-side heat insulating body 48. The second heat flowmeasurement system 46 measures the second heat flow Ipb flowing from theoutput-side thermal conductive plate 33B to the upper side of the secondheat flow measurement system 46 based on the temperatures T3 and T4measured by the second input-side temperature sensor 12 and the secondoutput-side temperature sensor 14, respectively.

The second input-side heat insulating body 47 is positioned on thesurface of the substrate 43 to cover the second input-side temperaturesensor 12. The second input-side heat insulating body 47 preferably hasa sheet shape and is made of a material, such as urethane, for example,having a low thermal conductivity. The second input-side temperaturesensor 12 is sandwiched between the second input-side heat insulatingbody 47 and the substrate 43.

The second input-side heat insulating body 47 has a predeterminedthickness dimension. Accordingly, the second input-side heat insulatingbody 47 has the predetermined thermal resistance value R3 between thesecond input-side temperature sensor 12 and the second output-sidetemperature sensor 14 depending on the thickness dimension. In thiscase, the second input-side heat insulating body 47 preferably has athickness dimension greater than that of the first input-side heatinsulating body 7 in order to differentiate the heat flow value of thefirst heat flow Ipa from the heat flow value of the second heat flowIpb. Accordingly, the thermal resistance value R3 of the secondinput-side heat insulating body 47 is higher than the thermal resistancevalue R1 of the first input-side heat insulating body 7.

The second output-side heat insulating body 48 is positioned on thesecond input-side heat insulating body 47 to cover the secondoutput-side temperature sensor 14. The second output-side heatinsulating body 48 preferably has a sheet shape and is made of amaterial, such as urethane, for example, having a low thermalconductivity. The second output-side temperature sensor 14 is sandwichedbetween the second output-side heat insulating body 48 and the secondinput-side heat insulating body 47.

The second output-side heat insulating body 48 is sandwiched between thesecond output-side temperature sensor 14 and the outside air. The secondoutput-side heat insulating body has a predetermined thicknessdimension. Accordingly, the second output-side heat insulating body 48has the predetermined thermal resistance value R4 between the secondoutput-side temperature sensor 14 and the outside air depending on thethickness dimension. In order to reduce or prevent the influence of thethermal contact resistance, for example, the second output-side heatinsulating body 48 and the second input-side heat insulating body 47preferably have the same or substantially the same thermal conductivity.

The sum (Ra+R1+R2) of the thermal resistances of the first thermalresistance body 34, the first input-side heat insulating body 7, and thefirst output-side heat insulating body 9 is preferably set so as to bedifferent from the sum (Rb+R3+R4) of the thermal resistances of thesecond thermal resistance body 35, the second input-side heat insulatingbody 47, and the second output-side heat insulating body 48, as in thefirst preferred embodiment described above. As a result, the first heatflow Ipa has a value different from that of the second heat flow Ipb.

The harvesting IC 49 is provided on the substrate 43 and is connected toa battery 54 and the arithmetic processing circuit 20 via the voltagestabilizing circuit 51 described below. The harvesting IC 49 defines andfunctions as, for example, the charging circuit. The harvesting IC 49receives radio waves externally transmitted in a wireless manner withthe harvesting antenna 50, converts the radio waves into electric power,and charges the battery 54 with the electric power. The harvesting IC 49may have a configuration in which the core body temperature Tcore of thesubject O, calculated by the arithmetic processing circuit 20, isexternally transmitted using the harvesting antenna 50.

The voltage stabilizing circuit 51 is provided on the substrate 43 andis connected between the harvesting IC 49 and the arithmetic processingcircuit 20. The voltage stabilizing circuit 51 maintains the voltage ofa power signal from the harvesting IC 49 at a constant value andsupplies the power signal to the battery 54.

The main body 52 preferably has, for example, a rectangular orsubstantially rectangular parallelepiped shape or a box shape havingstiffness with a thickness, as illustrated in FIG. 5 and FIG. 6. Themain body 52 includes the battery 54, a wireless IC 55, a transmissionantenna 56, a memory 57, and other components. The main body 52 includesa main-body-side connection terminal 53A to be connected to thesubstrate-side connection terminal 44A and a main-body-side connectionterminal 53B to be connected to the substrate-side connection terminal44B in order to communicate with the arithmetic processing circuit 20and the harvesting IC 49 at the substrate 43 side (refer to FIG. 6). Themain body 52 defines a repeatedly usable module, unlike the substrate43, which is a disposable portion.

The battery 54 is positioned in the main body 52 and is preferablydefined by, for example, an electric double layer capacitor. The battery54 is connected to the voltage stabilizing circuit 51 via themain-body-side connection terminal 53B and the substrate-side connectionterminal 44B. Electric power is supplied from the harvesting IC 49 tothe battery 54 and the battery 54 supplies the stored electric power tothe arithmetic processing circuit 20 and other components. The battery54 may not be an electric double layer capacitor and, for example, mayhave a configuration using a secondary battery.

The wireless IC 55 is positioned in the main body 52 and is preferablydefined by, for example, a wireless communication standard usingBluetooth (registered trademark). The wireless IC 55 is connected to thearithmetic processing circuit 20 via the main-body-side connectionterminal 53A and the substrate-side connection terminal 44A. Thewireless IC 55 defines and functions as the transmission circuit, whichtransmits the core body temperature Tcore of the subject O, calculatedby the arithmetic processing circuit 20 using the first heat flowmeasurement system 5 and the second heat flow measurement system 46, toan external device via the transmission antenna 56. In this case, thewireless IC 55 may store the calculated core body temperature Tcore inthe memory 57.

A process of assembling the core body thermometer 41 will now bedescribed with reference to FIG. 7 and FIG. 8.

First, as illustrated in FIG. 7, the respective temperature sensors 6,8, 12, and 14, the temperature measurement circuit 18, the arithmeticprocessing circuit 20, the harvesting IC 49, the harvesting antenna 50,the voltage stabilizing circuit 51, and other components are mounted onthe substrate 43. Then, the first input-side heat insulating body 7 isfixed on the first input-side temperature sensor 6 and the secondinput-side heat insulating body 47 is fixed on the second input-sidetemperature sensor 12.

Next, as illustrated in FIG. 8, the first arm portion 43B of thesubstrate 43 is folded back toward the heat receiving portion 43A sideto place the first output-side temperature sensor 8 on the firstinput-side heat insulating body 7. Similarly, the second arm portion 43Cof the substrate 43 is folded back toward the heat receiving portion 43Aside to place the second output-side temperature sensor 14 on the secondinput-side heat insulating body 47. Then, the first output-side heatinsulating body 9 is fixed on the first output-side temperature sensor 8and the second output-side heat insulating body 48 is fixed on thesecond output-side temperature sensor 14.

Here, the first heat flow measurement system 5 is spaced away from thesecond heat flow measurement system 46 to provide the gap 17 between thefirst heat flow measurement system 5 and the second heat flowmeasurement system 46. Finally, the main body 52 is placed on the firstoutput-side heat insulating body 9 and the second output-side heatinsulating body 48 and the substrate-side connection terminals 44A and44B are connected to the main-body-side connection terminals 53A and53B, respectively, to complete the core body thermometer 41.

As described above, substantially the same effects and advantages asthose of the first preferred embodiment are achieved in the thirdpreferred embodiment. According to the third preferred embodiment, thecore body thermometer 41 has a configuration including the harvesting IC49 capable of being charged with the radio waves externally transmittedin a wireless manner and the wireless IC 55 capable of externallytransmitting the core body temperature Tcore of the subject O.Accordingly, since the core body thermometer 41 is capable of being usedwith no cable and the wiring is not used in the measurement of the corebody temperature Tcore, it is possible to improve non-invasiveness.

In the configuration in the third preferred embodiment, the firstthermal resistance component is preferably used as the first thermalresistance body 34 and the second thermal resistance component is usedas the second thermal resistance body 35, as in the second preferredembodiment. However, the present invention is not limited to thisconfiguration and the configuration may be provided, as in the firstpreferred embodiment, in which the first thermal resistance layer isprovided between the substrate and the first input-side heat insulatingbody as the first thermal resistance body and the second thermalresistance layer is provided between the substrate and the secondinput-side heat insulating body as the second thermal resistance body.

A core body thermometer 1A according to a fourth preferred embodiment ofthe present invention will now be described with reference to FIG. 9. Adescription of the same components as those in the first preferredembodiment described above and the components similar to those in thefirst preferred embodiment described above is simplified or omittedherein and only different points will be primarily described. FIG. 9 isa cross-sectional view illustrating the configuration of the core bodythermometer 1A according to the fourth preferred embodiment. The samereference numerals are used in FIG. 9 to identify the same components asthose in the first preferred embodiment described above and thecomponents similar to those in the first preferred embodiment describedabove.

The core body thermometer 1A differs from the core body thermometer 1according to the first preferred embodiment described above in that thecore body thermometer 1A includes a first heat flow measurement system5A, instead of the first heat flow measurement system 5, and a secondheat flow measurement system 11A, instead of the second heat flowmeasurement system 11. The first heat flow measurement system 5A differsfrom the first heat flow measurement system 5 described above in thatthe first heat flow measurement system 5A does not include the via 2Aand the thermal conductive plate 4A and a substrate 2 having thepredetermined thermal resistance value Rc has the function of the firstthermal resistance body 10, instead of the first thermal resistance body10 having the predetermined thermal resistance value Ra. The second heatflow measurement system 11A differs from the second heat flowmeasurement system 11 described above in that the second heat flowmeasurement system 11A does not include the via 2B and the thermalconductive plate 4B and the substrate 2 having the predetermined thermalresistance value Rc has the function of the second thermal resistancebody 16, instead of the second thermal resistance body 16 having thethermal resistance value Rb.

The first heat flow measurement system 5A is positioned on the upperside of the substrate 2. The first heat flow measurement system 5Aincludes the first input-side temperature sensor 6, the first input-sideheat insulating body 7, the first output-side temperature sensor 8, andthe first output-side heat insulating body 9. In the first heat flowmeasurement system 5A, the first input-side temperature sensor 6 and thefirst output-side temperature sensor 8 are located at differentpositions along a path on which the first heat flow Ipa, which isdivided and flows into the core body thermometer 1A via the heatreceiving terminal 3 and the substrate 2, flows. With the aboveconfiguration, the first heat flow measurement system 5A measures thefirst heat flow Ipa flowing from the substrate 2 to the upper side ofthe first heat flow measurement system 5A based on the temperatures T1and T2 measured by the first input-side temperature sensor 6 and thefirst output-side temperature sensor 8, respectively.

The second heat flow measurement system 11A is provided on the upperside of the substrate 2. The second heat flow measurement system 11Aincludes the second input-side temperature sensor 12, the secondinput-side heat insulating body 13, the second output-side temperaturesensor 14, and the second output-side heat insulating body 15. In thesecond heat flow measurement system 11A, the second input-sidetemperature sensor 12 and the second output-side temperature sensor 14are located at different positions on a path on which the second heatflow Ipb, which is divided and flows into the core body thermometer 1Avia the heat receiving terminal 3 and the substrate 2, flows. With theabove configuration, the second heat flow measurement system 11Ameasures the second heat flow Ipb flowing from the thermal conductiveplate 2A to the upper side of the second heat flow measurement system11A based on the temperatures T3 and T4 measured by the secondinput-side temperature sensor 12 and the second output-side temperaturesensor 14, respectively.

The sum (Rc+R1+R2) of the thermal resistances of the substrate 2, thefirst input-side heat insulating body 7, and the first output-side heatinsulating body 9 is preferably set so as to be different from the sum(Rc+R3+R4) of the thermal resistances of the substrate 2, the secondinput-side heat insulating body 13, and the second output-side heatinsulating body 15. As a result, the first heat flow Ipa has a valuedifferent from that of the second heat flow Ipb. Since the remainingconfiguration is the same as or similar to that of the first preferredembodiment described above, a detailed description of the remainingconfiguration is omitted herein.

According to the present preferred embodiment, the core body temperatureis capable of being estimated with the heat from the subject O beinginput into the core body thermometer 1A at one node with no heat sourcefor heat generation, as in the first preferred embodiment describedabove. In particular, according to the present preferred embodiment, thesubstrate 2 preferably has the predetermined thermal resistance value Rcand the substrate 2 is able to be used as the first thermal resistancebody 10 and the second thermal resistance body 16 described above. Inother words, the substrate 2 preferably also has the functions of thefirst thermal resistance body 10 and the second thermal resistance body16. Accordingly, it is possible to further simplify the structure of thecore body thermometer 1A to reduce the size and the weight (make theprofile low) and to reduce the cost.

A core body thermometer 31A according to a fifth preferred embodiment ofthe present invention will now be described with reference to FIG. 10.FIG. 10 is a cross-sectional view illustrating the configuration of thecore body thermometer 31A according to the fifth preferred embodiment.The same reference numerals are used in FIG. 10 to identify the samecomponents as those in the second preferred embodiment described aboveand the components similar to those in the second preferred embodimentdescribed above.

The core body thermometer 31A differs from the core body thermometer 31according to the second preferred embodiment described above in that thecore body thermometer 31A includes a second heat flow measurement system11B, instead of the second heat flow measurement system 11. The secondheat flow measurement system 11B differs from the second heat flowmeasurement system 11 described above in that the second heat flowmeasurement system 11B does not include the second output-side heatinsulating body 15.

The second heat flow measurement system 11B is provided on the upperside of the thermal conductive plate 33B. The second heat flowmeasurement system 11B includes the second input-side temperature sensor12, the second input-side heat insulating body 13, and the secondoutput-side temperature sensor 14. In the second heat flow measurementsystem 11B, the second input-side temperature sensor 12 and the secondoutput-side temperature sensor 14 are located at different positionsalong a path on which the second heat flow Ipb flows. With thisconfiguration, the second heat flow measurement system 11B measures thesecond heat flow Ipb flowing from the thermal conductive plate 33B tothe upper side of the second heat flow measurement system 11B based onthe temperatures T3 and T4 measured by the second input-side temperaturesensor 12 and the second output-side temperature sensor 14,respectively.

The sum (Ra+R1+R2) of the thermal resistances of the first thermalresistance body 34, the first input-side heat insulating body 7, and thefirst output-side heat insulating body 9 is preferably set so as to bedifferent from the sum (Rb+R3) of the thermal resistances of the secondthermal resistance body 35 and the second input-side heat insulatingbody 13. As a result, the first heat flow Ipa has a value different fromthat of the second heat flow Ipb. Since the remaining configuration isthe same as or similar to that of the second preferred embodimentdescribed above, a detailed description of the remaining configurationis omitted herein.

According to the present preferred embodiment, the core body temperatureis capable of being estimated with the heat from the subject O beinginput into the core body thermometer 31A at one node with no heat sourcefor heat generation, as in the second preferred embodiment describedabove. In particular, according to the present preferred embodiment,omitting the second output-side heat insulating body 15 enables theconfiguration of the core body thermometer 31A to be further simplifiedto reduce the size and the weight (make the profile low) and to reducethe cost.

Although the preferred embodiments of the present invention have beendescribed, the present invention is not limited to the preferredembodiments and various modifications may be made. For example, aconfiguration may be provided in which either of the first output-sideheat insulating body 9 and the second output-side heat insulating body15 of the core body thermometer 1A according to the fourth preferredembodiment is not provided or both of the first output-side heatinsulating body 9 and the second output-side heat insulating body 15 arenot provided. In addition, a configuration may be provided in which acombination of the first heat flow measurement system 5A and the secondheat flow measurement system 11A of the core body thermometer 1Aaccording to the fourth preferred embodiment with the first heat flowmeasurement system 5 and the second heat flow measurement system 11 ofthe core body thermometer 1 according to the first preferred embodimentis used.

Although the configuration is provided in which the first output-sideheat insulating body 9 is provided and the second output-side heatinsulating body 15 is not provided in the fifth preferred embodimentdescribed above, a configuration may be provided in which the secondoutput-side heat insulating body 15 is provided and the firstoutput-side heat insulating body 9 is not provided. Alternatively, aconfiguration may be provided in which both of the first output-sideheat insulating body 9 and the second output-side heat insulating body15 are not provided.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A core body thermometer that estimates a corebody temperature of a subject based on a first heat flow and a secondheat flow flowing from the subject, the core body thermometercomprising: a substrate; a heat receiving terminal provided on or in thesubstrate, with which heat from the subject is received, and whichdivides the heat into the first heat flow and the second heat flow andcauses the first heat flow and the second heat flow to flow out; a firstheat flow measurement system that measures the first heat flow using afirst input-side temperature sensor located at an upstream side of thefirst heat flow and a first output-side temperature sensor located at adownstream side of the first heat flow; a second heat flow measurementsystem that measures the second heat flow using a second input-sidetemperature sensor located at an upstream side of the second heat flowand a second output-side temperature sensor located at a downstream sideof the second heat flow; a first thermal resistance body providedbetween the heat receiving terminal and the first input-side temperaturesensor and having a predetermined thermal resistance value; and a secondthermal resistance body provided between the heat receiving terminal andthe second input-side temperature sensor and having a predeterminedthermal resistance value.
 2. The core body thermometer according toclaim 1, wherein the first thermal resistance body is a first thermalresistance layer located between the heat receiving terminal and thefirst input-side temperature sensor; and the second thermal resistancebody is a second thermal resistance layer located between the heatreceiving terminal and the second input-side temperature sensor.
 3. Thecore body thermometer according to claim 1, wherein the first thermalresistance body is a first thermal resistance component; and the secondthermal resistance body is a second thermal resistance component.
 4. Thecore body thermometer according to claim 1, further comprising: one pairof thermal conductive plates sandwiching the substrate with the heatreceiving terminal; and a plurality of vias passing through thesubstrate and connecting the heat receiving terminal to the one pair ofthermal conductive plates; wherein the first thermal resistance body isprovided between one of the pair thermal conductive plates and the firstinput-side temperature sensor; and the second thermal resistance body isprovided between another of the pair of thermal conductive plates andthe second input-side temperature sensor.
 5. The core body thermometeraccording to claim 1, further comprising: a first input-side heatinsulating body disposed between the first input-side temperature sensorand the first output-side temperature sensor so as to cover the firstinput-side temperature sensor; and a second input-side heat insulatingbody disposed between the second input-side temperature sensor and thesecond output-side temperature sensor so as to cover the secondinput-side temperature sensor.
 6. The core body thermometer according toclaim 5, further comprising a first output-side heat insulating bodythat covers the first output-side temperature sensor and/or a secondoutput-side heat insulating body that covers the second output-sidetemperature sensor.
 7. The core body thermometer according to claim 1,further comprising: a charging circuit that charges the core bodythermometer with electric power that is externally supplied in awireless manner; and a transmission circuit that externally transmitsthe core body temperature of the substrate, which is estimated with thefirst heat flow measurement system and the second heat flow measurementsystem.
 8. The core body thermometer according to claim 1, wherein thesubstrate has a flat plate shape and is made of an insulating material.9. The core body thermometer according to claim 1, wherein the substrateis made of polyimide.
 10. The core body thermometer according to claim1, wherein the substrate has a thermal conductivity lower than that ofthe subject.
 11. The core body thermometer according to claim 1, whereinthe heat receiving terminal has a flat plate shape or a film shape. 12.The core body thermometer according to claim 1, wherein the heatreceiving terminal is made of a material having a thermal conductivityhigher than that of the subject.
 13. The core body thermometer accordingto claim 1, wherein the heat receiving terminal is made of aluminum.